Palladium(II)-catalyzed direct alkenylation and arylation of arenes: removable 2-pyridylsulfinyl group assisted C-H bond activation

Palladium-catalyzed C-H activation reactions directed by a removable 2-pyridylsulfinyl group were developed. Aromatic olefination products were formed in good yields on treatment of 2-(phenylsulfinyl)pyridines with alkenes in the presence of a Pd catalyst. The reaction tolerates a wide range of substituted alkenes, including various acrylates and styrenes. The controlled experiments indicated that the 2-pyridyl moiety, rather than the sulfinyl, played the role of ligand. The final reductive desulfonylation affords the stilbenes, sulfides, and disulfides with different reductive conditions, respectively. More importantly, this transformation could also be applied in arylation through dual C-H activation.